Magnetic resonance imaging evaluation and arthroscopic resection of localized pigmented villonodular synovitis of the knee

Diagnosis of localized pigmented villonodular synovitis is clinically diffi cult, and plain radiographs are usually normal. This article presents five patients with localized pigmented villonodular synovitis of the knee. Sympt oms suggested a meniscal lesion in three patients and a loose body in two. Magnetic resonance imaging performed prior to arthroscopic resection reveal ed a preoperative diagnosis of a tumor in all five patients. Magnetic reson ance imaging is a valuable clinical tool for the assessment of intra-articu lar soft-tissue tumors of the knee that may otherwise be misdiagnosed.